This invention is related to the field of catalysts for producing carbon nanotubes and methods of their use, and more particularly, but not by way of limitation, single-walled carbon nanotubes, and to methods to produce polymers and products comprising carbon nanotubes.
Carbon nanotubes (CNTs) are seamless tubes of graphite sheets with full fullerene caps which were first discovered as multi-layer concentric tubes or multi-walled carbon nanotubes (MWNTs) and subsequently as single-walled carbon nanotubes (SWNTs) in the presence of transition metal catalysts. Carbon nanotubes have shown promising applications including nanoscale electronic devices, high strength materials, electron field emission, tips for scanning probe microscopy, and gas storage.
Generally, single-walled carbon nanotubes are preferred over multi-walled carbon nanotubes for use in these applications because they have fewer defects and are therefore stronger and more conductive than multi-walled carbon nanotubes of similar diameter. Defects are less likely to occur in SWNTs than in MWNTs because MWNTs can survive occasional defects by forming bridges between unsaturated carbon valances, while SWNTs have no neighboring walls to compensate for defects.
SWNTs in particular exhibit exceptional chemical and physical properties that have opened a vast number of potential applications.
However, the availability of CNTs and SWNTs in particular in quantities and forms necessary for practical applications is still problematic. Large scale processes for the production of high quality SWNTS are still needed, and suitable forms of the SWNTs for application to various technologies are still needed. It is to satisfying these needs that the present invention is directed.
Previous U.S. patents and applications directed to catalysts and methods of producing carbon nanotubes, including U.S. Pat. No. 6,333,016, U.S. Pat. No. 6,413,487, U.S. Published Application 2002/0165091 (U.S. Ser. No. 09/988,847), and U.S. Published Application 2003/0091496 (U.S. Ser. No. 10/118,834), are hereby expressly incorporated by reference herein in their entireties.